There has been a long-felt need for a mold and method for injection molding a sole onto an upper made of textile, vinyl, suede, leather on any other suitable materials by which a shoe is produced very economically in which the lower periphery of the sole slopes downwardly and inwardly and forms a downwardly extending continuation of the peripheral face of the bumper. In addition, the mold should be capable of using a single sole plate to produce a shoe in which the bumper and integral first sole part is formed of one color of injection molding material and a second sole part is formed of another color of injection molding material with the periphery of the second sole part visible from the sides and ends of the shoe beneath the bumper to provide an attractive two-color exterior appearance for the bumper and the second sole part. Furthermore, the upper surface of the sole plate should be capable of producing a skid-resistant surface on the bottom surface of the sole.
While DiPaolo U.S. Pat. No. 3,806,974 discloses a mold and method for injection molding a sole onto a textile upper using a single sole plate to produce a shoe in which the bumper and an integral first sole part is formed of one color of injection molding material and a second sole part is formed of another color of injection molding material and in which the surface of the sole plate is capable of producing a skid-resistant surface on the bottom surface of the sole, the lower periphery of the DiPaolo's sole does not slope downwardly and inwardly and does not form a downwardly extending continuation of the peripheral face of the bumper. Furthermore, the periphery of DiPaolo's second sole part is not visible from the sides and ends of the shoe.
British Pat. No. 1,173,260 discloses a relatively expensive method of making a shoe in which the sole plate or plunger 11 is moved upwardly to compress the injection molding material after each injection step. Like DiPaolo, the lower periphery of the sole produced by the mold and method of this patent does not slope downwardly and inwardly and its second sole part is not visible from the sides and ends of the shoe in the embodiment of FIG. 3.
A shoe has been manufactured and sold by Puma of Germany and imported and sold in this country by Beconta Inc. which has a leather upper, a white vulcanized rubber bumper and first sole part and a blue vulcanized rubber second sole part beneath the bumper and first sole part. The second sole part has a skid-resistant bottom surface. Two different sole plates are used to produce the Puma shoe, one to produce the white bumper and integral first sole part and another to produce the blue second sole part which has a surface capable of producing the skid-resistant bottom surface of the second sole part.
With Puma, the combined bumper and first sole part and the second sole part are first manufactured using two sole plates and this process consumes about 21/2 minutes. Then the combined bumper, first sole part and second sole part are attached to the upper by cement and this is a very time consuming step.
With my mold and process, only about 2-1/2 seconds are required to mold the combined bumper and first sole part, about 56 seconds to cool it and cause it to adhere to the bottom of the lasted upper, only about 21/2 seconds to mold the sole part and about 36 seconds to cool it, making a total elapsed time of one minute and 37 seconds with no time consuming cementing step.
Consequently the Puma shoe is much more expensive to manufacture than a shoe made by the mold and method of my invention.
Tusa et al U.S. Pat. No. 3,441,643 discloses a well known prior art method and mold for injection molding a sole onto a textile upper but the Tusa et al patent produces only a single layer sole and the Tusa mold and method are relevant only to show a well known prior art method which has been extensively used in the United States for many years.
The above described prior art is the closest prior art to the mold and method of this invention of which I am aware.